Process of removing engine carbon



Patented May is, 1933 UNITED. STATES PATENT OFFICE CLARENCE J. LIVINGBTONE AND SAMUEL P. HARLEY, OF PITTSBURGH, PENNSYL- VANIA, ASSIGNORS TO GULF REFINING GOMIBANY, OF PITTSBURGH, PENNSYL- VANIA, A CORPORATION OF TEXAS PBOORS OF REMOVING ENGINE CARBON Ho Drawing.

This invention relates to processes of removing engine carbon; and it comprises a process wherein the carbon deposits in gasoline engine cylinders are treated with a small quantity of a pyroxylin solution, said solution containing a solvent capable of blending with tar and the like and the treated carbon, is afterwards exposed to beat; all as more fully hereinafter set forth and as claimed. i a

In spite of its hard and reslstant nature, the so-called carbon deposit in the gasoline engine cylinders must be regarded as a sort of concrete in which an aggregate of particles of actual coke is bonded b a matrix of tar or pitch. Mechanically, t 1s deposit is often hard, strong and resistant and its removal is frequently a matter of considerable difiieulty. All sorts of carbon removing liquids have been proposed; most of these implicitly, though not often explic tly, having the function of entering thedeposlt and dissolving the tarry or pitchy binder. Insofar as these liquids are of an all hatic hydrocarbon nature they are ver litt e eflicacious for the reason that the material resistant to gasoline, and therefore to most similar hydrocarbons. Benzol compositions are somewhat more efiicient.

In the present invention carbon is peeled off, disintegrated and removed by a sort of compound action, partly mechanical.

We have discovered that the carbon deosit can be removed from the metal suraces of the combustion chamber by allowing a film of glue or similar material to form and dry over the deposit. This film when taken off mechanically, or on separating spontaneously by drying, strips the carbon deposit off with it. Thisis true even when the deposit is excessively hard and adherent. A similar effect is obtained when the film is composed of a pyroxylin or nitro cotton lacquer material instead of glue; The action of the film in taking off the carbon deposit is facilitated in this case because the lacquer solvents contain materials which soak into the deposit dissolving the tarry binder and softening the whole mass. This does not occur so readily with the aqueous medium in inder is a.

Application am m 14, 1930. Serial No. 401,905.-

which glue is dissolved. The softening act1on of the lacquer solvents may be adjusted by changing the solvents themselves and their volatility may be controlled so that they evaporate at the proper rate, leaving a coherent pyroxylin film in a short time. While aglue film in a combustion chamber can decomposed by'running the engine, thus dlstmtegrating and ejecting the deposit, such an action occurs much more readily with a film of pyroxylin which decomposes rapidly as soon as heat is applied.

Qur preferred manner of treating the deposit in our present invention is to treat the same with a solution of pyroxylin, or soluble gun cotton, in one or more of a number of solvents. These pyroxylin solutions are in part colloidal in their character and to this extent such pyroxylin may not penetrate far into the coating save where cracks and fissures occur. On the other hand, the solvents and some film pyro lin are taken up by the pitchy or tarry bin er of the carbon concrete in the engine, and thus weaken the coked structure. These pyroxylin solutions are of such a concentration that as the solvent is removed the shrinkage in forming a pyroxylin layer is eat. This contraction of a shrunk film un er tension is due to the natural evaporation of the solvent from the outer surface.' Such a film, once formed, already contains much of the carbon deposit.

On exposure of the treated carbon deposit to heat a number of things hap en, all conducing to the disintegration an removal of the carbon deposit. The remaining absorbed solvent is volatilized and its volatilization may be more or less explosive. The pyroxylin which has put the coating under strain and such as has impregnated the deposits decomposes with a further disintegrating effect. In practice it is found that when the treated deposit comes under heat it shells and peels off, sometimes (at first) in rather large fragments, leaving practically clean metal behind. The large fra ents rapidly disintegrate into a powder w ichis blown out with the exhaus The pyroxylin solution may be squirted or sprayed into the cold cylinder, the cylinder allowed to stand for a short time and then the engine put in operation. The solution may be forced into the cylinders and the excess siphoned oif; or the solution may be used as a paint for the inner surfaces when the head is removed. The film'separates easily bringing the coke with it. In making a pvroxylin solution for the present purposes, Olt inary celluloid or scrap from photo graphic film may be employed; and most of the ordinary solvents are efiicacious for the present purposes. Better results, however, are obtained by special solvents. Most pyroxylin solutions contain large amounts of what are called non-solvents, generally benzol or toluol. Unlike gasoline, these aromatic hydrocarbons are taken up rather freely by the tarry matrix of the carbon deposit softening the deposit as a whole. Coal tar light oils are usually a desirable component of the present carbon remover. However, pyroxylin dissolved in a mixture of acetone and benzol or in one of acetone and coal tar light oil'works well, as does a mixture of ethylene dichlorid, ethyl acetate and monoethyl amine. Acetone alone as a solvent for pyroxylin works, but acetone mixtures are better. Ordinarily, the amount of pyroxylin used in the carbon remover may range from 1 or 2 for cent up to or 8 per cent. The limit 0 concentration is in general the viscosity of the solution.

In using these pyroxylin solutions is removing carbon deposit from the lnterlor of engine cylinders it has been found that explosion of the pyroxylin is not really necessary, in any case, for removal of tl 1e deposits. However, rapid decomposition is readily efiected when the engine is put into use and the fine carbon blows out through the exhaust harmlessly.

The peeling and explosive functions of the nitro-cellulose are important factors in the carbon removal and the blending of a little pyroxylin with the various tar solvents which have been proposed for removing carbon, materially improves their efiiciency.

In general most of the wide range of solvents ordinarily effective for pyroxylin may be used; but the efiectiveness of the process may be improved by the addltion of solvents designed especially to penetrate and soften the binder of the carbon deposit or to promote wetting action of the deposit. The usual procedure is to make up the concentrated solution of pyroxylin in ethyl alcohol or ethyl acetate, or in some acetone mixture, and then to dilute this solution with appropriate solvents or softeners for the deposit to bring about the desired penetration. Examples of such substances are ehlorbenzene, brombenzene, dichlorethyl ether, ethylene dichloride, quinoline, secondary butyl acetate, cresols, aniline, and furfural. These substances may be introduced posit and formation of film the procedure may be modified in such a way that a dilute solution of the pyroxylin or one of the above mentioned deposit softening solvents is first applied. After a short interval of time a moreconccntratcd solution of quicker drying properties is introduced. Improved results may even be obtained by several applications of the same solution with time intervals for allowing penetration.

In a specific remover made under the present invention about 16.5 parts by weight of commercial lacquer nitrocotton were dissolved in a mixture of 50.5 parts of ethyl alcohol and 33 parts ethyl acetate, and this solution was diluted with an equal weight of a mixture of equal quantities of benzene and chlorbenzene.

In another example the above stock solu tion of nitro-cotton in ethyl alcohol and ethyl acetate was diluted with an equal weight of ethylene dichloride. The final composition of the mixture was 8.25 parts nitrocotton, 25.25 parts ethyl alcohol, 16.5

parts ethyl acetate and 50 parts ethylene dichloride.

In the above examples allowance has been made for the ethyl alcohol with which the nitrocotton is wet for convenient handling.

What we claim is:

1. The process of removing carbon from internal combustion engines and the like which comprises coating the deposit with a penetrating, film forming composition suitable for producing a peeling film, allowing the film to form and to peel and then removing the said film together with the engine carbon loosened by the action of said 2. The process of claim 1 in which the film forming composition comprises a dilute solution of pyroxylin.

3. The process of claim 1 in which the film forming composition comprises a solution containing solvents suitable for penetrating and softening the tarry binder of said carbon deposit.

4. The process of removing carbon from internal combustion engines and the like which comprises applying to said engine carbon a pyroxylin composition containing a solvent suitable for penetrating and softening the tarry binder of the carbon deposit selected from a class consisting of benzol,

toluol, coal tar light oils, acetone,

ethylene dichlorid, ethyl acetate, monoethyl amine, chlorbenzene, brombenzene, dichlorethyl ether, quinoline, secondary butyl acetate, cresols, aniline and furfural, permitting a film to form and thereafter removing the resulting film together with the engine carbon loosened by the action of said film.

5. The process of removing carbon from internal combustion engines and the like which comprises applying to the surface of the carbon deposit a penetrating pyroxylin composition, suitable for producing a peeling film, allowing a film to form, decomposing the resulting film with heat and removing the residues of film and of carbon loosened by the action of said film.

6. The process of claim 5 in which the py roxylin solution is a dilute solution of pyroxylin in a solvent having the properties of penetrating and softening the tarry binder of said carbon deposit.

7. The process of removing carbon from internal combustion engines and the like which comprises applying to the surface of the carbon deposit a dilute solution of pyroxylin in a solvent having the properties of penetrating and softening the tarry binder of said carbon deposit and thereafter applying to said surface a-more concentrated pyroxylin solution having quicker dr ing prolperties, permitting the solution to orm a ti m and t ereafter removing the said film and the carbon loosened by the action of said 8. The process of removing carbon from internal combustion engines and the like which comprises applying to the surface of the carbon de osit a composition comprising pyroxylin, et yl alcohol, ethyl acetate, benzene and chlorbenzene, permitting a film to form and then removing the resulting film together with the engine carbon loosened by the action of said film.

In testimony whereof, we have hereunto affixed our signatures.

CLARENCE J. LIVINGSTONE. SAMUEL ,P. MARLEY. 

